site_archiver@lists.apple.com Delivered-To: Darwin-kernel@lists.apple.com I'm toying with how the IDT is handled in XNU. Basically I need to setup my own IDT via LIDT. Apparently doing this via mp_rendezvous() (this is for a project involving a patch to the kernel source) and using the physical address returned by IOMallocContiguous won't help. Obviously I'm copying the original IDT and saving its original location to be restored eventually, albeit it's not required in this scenario. I come from a Linux kernel development background and never experienced this issue before, so I suppose I'm missing something specific to XNU. Does the returned phys addr truly contain a fixed address value? I asked because kmem_alloc API functions exist for the same purpose but they aren't even exported through com.apple.kernel. There was no pun intended there, at all. I was simply stating a fact. Since IOLib provides perfectly useful API for this, it's not a problem this time. -- Terry _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-kernel mailing list (Darwin-kernel@lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-kernel/site_archiver%40lists.a... On Dec 21, 2008, at 1:13 PM, "John D." <johndenkar@gmail.com> wrote: On Sun, Dec 21, 2008 at 10:03 PM, Michael Smith <msmith@mu.org> wrote: If you were to explain *why* you want this allocation, it might be easier to help you. We have supported API for this. Take a look at the WINE sources for example usage. If you are trying to take over the normal system call vector, though, that's not supported.

From a security perspective, if you wrote code that succeeded in doing this, I would feel more or less obligated to break it by declaring the kernel virtual address space off limits to modification by Mach vm_* API.

Mike already indicated that kernel memory allocations are wired. There is an API to get pageable kernel memory, but almost no one uses it (I know of one caller). Wired allocations have fixed physical addresses, by definition; that's what "wired" means. Give it a break already. I think Mike was merely pointing out that you'll be more likely to get useful responses if you don't make back-handed jabs at architectural decisions which have already been explained as to their purpose. This email sent to site_archiver@lists.apple.com